A Yellow Sun is a G-type main-sequence star (Spectral type: G-V), often (and imprecisely) called a yellow dwarf, or G dwarf star, is a main-sequence star (luminosity class V) of spectral type G. Such a star has about 0.8 to 1.2 solar masses and surface temperature of between 5,300 and 6,000 K. Such stars are massive (though several times smaller than an ancient red sun, like Krypton's Rao), luminous balls of plasma, held together by gravity, and they provide for and help sustain life on the planets orbiting them.
While Earth's yellow sun provides life to the planet, giving it heat to sustain life, it also has a dramatic effect on Kryptonians, members of a sophisticated interstellar race from the currently destroyed planet of Krypton. Compared to humans and even metahumans, Kryptonian aliens appear as gods, with all of their physical abilities and senses heightened 100 times over at least. They also gain separate abilities, such as the power to fly, see through opaque objects, and also project laser-like thick beams of heat from their eyes, as well as becoming virtually impenetrable. Due to these incredible powers of his, the Kryptonian Kal-El was promptly nicknamed "Superman". The more extensive a Kryptonian's solar-energy supply is, the stronger and more powerful he/she becomes, demonstrated by Kal-El being somewhat stronger than General Zod, Faora-Ul, and Nam-Ek, due to them having arrived on Earth relatively recently.